[InstCombine] Skip dbg.value(s) when looking at stack{save,restore}.

Fixes PR37713.

llvm-svn: 334317

2 files changed, 55 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 7526b2ea2c9..ca2b38dce28 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -3521,8 +3521,15 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
     // happen when variable allocas are DCE'd.
     if (IntrinsicInst *SS = dyn_cast<IntrinsicInst>(II->getArgOperand(0))) {
       if (SS->getIntrinsicID() == Intrinsic::stacksave) {
-        if (&*++SS->getIterator() == II)
+        // Skip over debug info instructions.
+        // FIXME: This should be an utility in Instruction.h
+        auto It = SS->getIterator();
+        It++;
+        while (isa<DbgInfoIntrinsic>(*It))
+          It++;
+        if (&*It == II) {
           return eraseInstFromFunction(CI);
+        }
       }
     }
 
diff --git a/llvm/test/Transforms/InstCombine/stacksave-debuginfo.ll b/llvm/test/Transforms/InstCombine/stacksave-debuginfo.ll
new file mode 100644
index 00000000000..3c31c4c78a9
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/stacksave-debuginfo.ll
@@ -0,0 +1,47 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; dbg.value instrinsics should not affect peephole combining of stacksave/stackrestore.
+; PR37713
+; RUN: opt -instcombine %s -S | FileCheck %s
+
+declare i8* @llvm.stacksave() #0
+declare void @llvm.stackrestore(i8*) #0
+
+define i32* @test1(i32 %P) !dbg !6 {
+; CHECK-LABEL: @test1(
+; CHECK-NEXT:    [[TMP1:%.*]] = zext i32 [[P:%.*]] to i64, !dbg !12
+; CHECK-NEXT:    [[A:%.*]] = alloca i32, i64 [[TMP1]], align 4, !dbg !12
+; CHECK-NEXT:    call void @llvm.dbg.value(metadata i32* [[A]], metadata !11, metadata !DIExpression()), !dbg !12
+; CHECK-NEXT:    ret i32* [[A]], !dbg !13
+;
+  %tmp = call i8* @llvm.stacksave(), !dbg !12
+  call void @llvm.dbg.value(metadata i8* %tmp, metadata !9, metadata !DIExpression()), !dbg !12
+  call void @llvm.stackrestore(i8* %tmp), !dbg !13
+  %A = alloca i32, i32 %P, !dbg !14
+  call void @llvm.dbg.value(metadata i32* %A, metadata !11, metadata !DIExpression()), !dbg !14
+  ret i32* %A, !dbg !15
+}
+
+declare void @llvm.dbg.value(metadata, metadata, metadata) #1
+attributes #0 = { nounwind }
+attributes #1 = { nounwind readnone speculatable }
+
+!llvm.dbg.cu = !{!0}
+!llvm.debugify = !{!3, !4}
+!llvm.module.flags = !{!5}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C, file: !1, producer: "debugify", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
+!1 = !DIFile(filename: "patatino.ll", directory: "/")
+!2 = !{}
+!3 = !{i32 4}
+!4 = !{i32 2}
+!5 = !{i32 2, !"Debug Info Version", i32 3}
+!6 = distinct !DISubprogram(name: "test1", linkageName: "test1", scope: null, file: !1, line: 1, type: !7, isLocal: false, isDefinition: true, scopeLine: 1, isOptimized: true, unit: !0, retainedNodes: !8)
+!7 = !DISubroutineType(types: !2)
+!8 = !{!9, !11}
+!9 = !DILocalVariable(name: "1", scope: !6, file: !1, line: 1, type: !10)
+!10 = !DIBasicType(name: "ty64", size: 64, encoding: DW_ATE_unsigned)
+!11 = !DILocalVariable(name: "2", scope: !6, file: !1, line: 3, type: !10)
+!12 = !DILocation(line: 1, column: 1, scope: !6)
+!13 = !DILocation(line: 2, column: 1, scope: !6)
+!14 = !DILocation(line: 3, column: 1, scope: !6)
+!15 = !DILocation(line: 4, column: 1, scope: !6)